April 20, 2011

Canadian Arctic Islands Play Big Role In Sea Level Rise

According to a new study, melting glaciers and ice caps on Canadian Arctic islands play a much greater role in sea level rise than scientists previously thought.

There are bout 30,000 islands within the 550,000-square-mile Canadian Arctic Archipelago.

The study found that between 2004 and 2009, the region lost the equivalent of three-quarters of the water in Lake Erie.

Alex Gardner, a research fellow in the Department of Atmospheric, Oceanic and Space Sciences at the University of Michigan, said in a statement that warmer-than-usual temperatures in those years caused a rapid increase in the melting of glacier ice and snow.

"This is a region that we previously didn't think was contributing much to sea level rise," Gardner said. "Now we realize that outside of Antarctica and Greenland, it was the largest contributor for the years 2007 through 2009. This area is highly sensitive and if temperatures continue to increase, we will see much more melting."

Ninety-nine percent of all the world's land ice is trapped in the massive ice sheets of Antarctica and Greenland. These account for just half of the land-ice being lost to oceans.

The other half of the land-ice melt added to sea-level rise comes from smaller mountain glaciers and ice caps like those in Canadian Arctic, Alaska, and Patagonia. Gardner said that this study underscores the importance of these smaller regions.

This region during first three years of the study lost an average of 7 cubic miles of water per year. That number increased to 22 cubic miles of water per year during the latter part of the study.

The study found that a one-degree increase in average air temperature resulted in 15 cubic miles of additional melting.

"This is a big response to a small change in climate," Gardner said in a statement. "If the warming continues and we start to see similar responses in other glaciated regions, I would say it's worrisome, but right now we just don't know if it will continue."

During the study, the researchers performed numerical simulations and then used two different satellite-based techniques to independently validate their model results.

The team also used a technique called "gravimetry" to measure changes in the Earth's gravitational field, which signified a redistribution of mass.

The study is published online in Nature on April 20.

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Image Caption: This is summer sea ice off the coast of Devon Island in Nunavut, Canada in August 2008. Credit: Alex Gardner